A typical prior art face grooving tool is shown, for example, in FIG. 2 of U.S. Pat. No. 5,709,508, in which a cutting insert is retained in a slot formed between an upper clamping jaw and a curved lower base jaw. The slot is open on each side of the cutting insert which not only weakens the structure of the cutting tool in the region of the slot and but also means that there is no natural retention of the cutting insert in the lateral direction leading to lateral instability of the cutting insert during metal cutting operations. Clearly, this is a problem not only with face grooving tools but also with non-face grooving tools. In order to stabilize the cutting insert against lateral forces, the jaws of the tool and the upper and lower surfaces of the cutting insert can be provided with convex-concave mating surfaces in the clamping region of the cutting insert as seen in FIG. 2 of U.S. Pat. No. 5,709,508, and shown more explicitly, for example, in FIGS. 3A and 3B of U.S. Pat. No. 6,234,727.
However, a disadvantage of convex-concave mating surfaces in the clamping region, when they are applied to both the upper and lower surfaces of the clamping portion of an insert is that it restricts the minimum size of the cutting insert thereby restricting the minimum groove diameter size that can be achieved.